Destructive distillation of solid carbonizable material



Patented Feb. 6, 1934 PATENT OFFICE Lewis C. Karrick, Salt Lake City,Utah Application April 14, 1928. Serial No. 270,030

5 Claims.

This invention relates to a process for the production of organic liquidproducts of controlled physical and chemical properties from coal andother solid carbonizable fuel materials.

The principal object of my invention is to produce directly from solidcarbonizable fuel substances a crude liquid tar oil which is lighterthan water.

A feature of the invention resides in continuously producing syntheticoil from solid carbonizable fuel materials and simultaneously extendingthe thermal decomposition of the oil so produced under controlledconditions to give an oil of lower density than water. This unusualproperty of the tar oil so produced obviates the necessity i'orsubsequent dehydration by distillation as well as the necessity forsubsequent cracking by auxiliary means.

The process also provides for the continuous disposal of the carbonformed in the 4thermal decomposition of tar oils 'by causing it to beintimately mixed with and deposited on the cell surfaces of thecarbonaceous materials treated. 'This enables the process to utilizeadvantageously low grade coals and other carbonaceous materials of highcarbon content for producing light oils without the necessity ofinterrupting the process to dispose of the carbon formed, or using rundown stills.

The tar oils produced from coals by the many proposed forms oflovwtemperature carbonizing processes or by accepted assay methods, areof higher density than water due to the high molecular weights of theingredients forming the tar oils and their high carbon-hydrogenelemental ratio. In general, the vdensity of the tar oil formed isgreater in inverse ratio to the amount of low temperature dissociationwhich is caused to take place. I have found that as the amount of lwtemperature decomposition of the oil forming bitumens is increased thedensity of the tar oils decreases and the carbon to hydrogenpercentagecomposition likewise decreases; this Vsupplies to the acidtars and the unsaturated hydrocarbons as Well as to the neutral oils.However. ii the tar oils are subjected to high temperature dissociationsas they are formed much of the tar is lost by conversion to fixed gaseswhile the density of the resulting tar is increased due principally topolymerization of a part of the tar oils which go to form the pitchresiduum. I, therefore, apply,

conditions in my process which accomplish controlled low temperaturepyrolysis of the primary btumens and of the tar oils, thereby resultingin a minimum of conversion to iixed gases or to (CL 21R- 16) polymerizedproducts and I reduce the carbon percentage in the oils simultaneouslywith a considerable reduction in their densities. I also applyconditions which catalyze these reactions as herein described.

In carrying out the invention, the materials to be treated arepreferably finely crushed in order that all the substance may receiveidentical heat treatment, which would not be the case if lumps ofconsiderable dimension were in process of heat- 05 ing for, or during,the same period of time. The process is well suited to destructivedistillation of the granular or dust size coal delivered to powerplants, or to rle sizes of oil shale. The process is also adapted toutilize accumulations of other low grade solid car-bonizable fuelmaterials which are common at mines, power plants, coke or gas plantsand the like. In the description of the process, the treatment of coalwill be described, but it is understood that other carbonaceousmaterlals may be treated similarly and like reactions will be obtained.I do not limit the treatment to any one carbonaceous substance, but havefound that improved results are in many cases obtained by using mixturesof solid ingre- 89 dients such as different grades of oil shales ofvarying richness and physical and chemical propu erties, or varioustypes of coals of varying rank, coking index, or coals with.mixtures ofcarbonaceous residue added.

In addition to the benets obtained in the fluid products by usingmixtures of solid ingredients in the reaction zones, 4Ifind that ifcertain of the liquid products are continuously mixed with the chargedmaterials, a. uniform and regulated de- 90 structive distillation orcracking takes place, and thereby any desired degree of modification oithe fluids can be carried out. The process is primarily for carrying outthe regulated thermal decomposition, or cracking, of the bitumen whichforms the primary decomposition product in the heat treatment of oilshales and coals so as to produce liquid oil products of any desiredgravity and volatility. Some of the primary products may mg be permittedto leave the cracking system with the highly volatile oils before thedesired ultimate degree of dissociation has taken place. This proceduremay be necessary for reasons of practicability in order to quicklyremove and protect the light volatiles which form oils of the desiredgravity before their excessive decomposition takes place. I thereforeprovide for the retention of the heavy or unfinished ingredients in thesystem and return them to the reaction chamber by controlled separatingmeans and subject them to further destructive distillation.

It is the purpose in the process to cause the thermal decomposition ofthe bitumens or primary liquid products to produce final distillates ofthe desired specic gravity by a series of heat treatments in thereaction chamber. In order that the distillation' products will not becarried out prematurely from the reaction chamber in a vapor orsuspended condition, I provide means for heating the materials under theproper pressures to elevate the vaporizing temperatures of theliquid'bitumens to points where the desired cracking will largely becompleted.

It is damaging to the quality of the oil products to permit the vaporsto linger in the highly heated zones and especially in contact with ironretort walls, and I provide means for minimizing any harmful eifectsfrom such causes. I prefer to cause the' vapors to move toward an exitin the direction of the feed endof the reaction chamber and into zonesof lower wall temperature, and thereby ilow counter tothe generalmovement ot the carbonaceous materials. The vapors may, however, beremoved at Ieither or at both ends if desired in producing specialproducts. Furthermore, means are provided for introducing steam,

oil, vapors, or gases at the discharge end, or into the distilling zoneso as to protect the distillation products by chemical reaction or bydilution and with change of temperature while sweeping them from the.chamber. I prefer also that ,the inner wall lsurface of the reactionchamber be copper or chromium plated to prevent formation of undesiredcompounds.

I have proved by my process that the highest quality oils from coals andoil shales are produced when the heating is very slow and with gradualrise of temperature. In order that the best rate and temperatures ofheating may be applied to thereacting substances, the carbonaceous andvolatile materials are each caused to move at controlled rates throughthe different heating zones while the zones are heated to differenttemperatures.

In applying the process conditions as stated above, I prefer to use arevolving retort of cylindrical form of standard pipe, its length beingmany times its diameter, for example: 3 20, 6 40, 12" 60 or 20" 100, inorder that there will be very little conducted, convected, or radiatedheat between theadjacent inside zones or between adjacent portions ofthe charge, through the retort walls or by the' retort contents. Theretort is set at .a slight angle from the horizontal so that thematerials treated will pass through by gravity during their uniformmotion during rotation. y

The cylinderI is heated externally throughout' vpart or all of itslength by hot gases or other suitable means. The oven surrounding thecylinder is divided into zones so that different portions of thecylinder and contents are heated to diiferent temperatures. In using alarge cylinder there may be walls or constrictions (not speciiicallyshown herein) extending different distances from the outer walls andserving as a means of damming the ilow of materials and retaining it fora greater or less period in the zones according to the height of thewalls. A slight modification in height of the constriction causes arelatively great diiference in the depth of charge and its rate ofprogress through the zone. If the carbonaceous material is preheated, byseparate means, close to its distillation temperature,

latthe second heating zone and thereby permit it will not be necessaryto use as many constrictions, or the entire chamber may vserve as asingle extended zone for carbonizing. The external heat will beregulated to increase the temperature of the material as it moves towardthe outlet. However, if some of the partly cracked bitumen has escapedfrom the chamber and is returned to complete its thermal decompositionit may be desirable to use a constriction possibly adequate crackingtime nearthe feed end of the chamber. As a result the vapors'will notcome into contact with the more highly heated walls toward the exit endof the chamber.

Tar oilswill crack and deposit a great deal of pitch carbon indistilling by ordinary methods to coke. Also, if the tar oil is firstmixed with nely divided coal an increased amount of light liquidproducts may be formed. However, I have found that when the same initialtar oil is mixed with coke, particularly a highly adsorptive lowtemperature "coke, and distilled preferably under pressure, a very muchgreater yield of valuable low boiling products is obtained. Ifv the cokehas ingredients adsorbed in its pores which react chemically 4with thetar oils the resulting product may be altered con iderably. I haveadsorbed metallic copper on t e cell surfaces of the coke and found thatit removed much of the sulphur from the tar oils. This treatment is alsoapplicable to petroleum. I produced such a treated coke by activatingthe carbonaceous residue from the process by contacting with a currentof superheated steam above 850 C. and immersing this cokel immediatelythereafter in a solution of copper chloride. Cobalt and chromium saltsmay also be used. I therefore prefer to charge continuously a quantityof the coke product, or other coke, either activated or unactivated,which may be'treated or not as de- 115 sired, into the retort with thecoal in ample amount to absorb the incompletely cracked primaryv tar oilwhich is returned to the reaction chamber and thereby greatly increasethe capacity and thoroughness oi the thermal decompositions desired byuse of this process.

By this process, a' highly reactive and adsorptive low temperature cokeproduct is produced, with any desired percentage of volatiles retained,

a large yield of rich gas, and a large yield oi tar oil which is mostlyof the same volatility as ordinary petroleum tops.

In the drawing: f

Fig. 1 is a diagrammatic illustration of apparatus embodying the processof the invention and is an elevation with parts largely in section; and

Fig. 2 is a cross-section taken on the line 2-2 of Fig. 1.

Referring to the drawing: Fig. 1 shows a 4rotary pretreater 1 heatedinternally with hot gases and 135 containing a multiplicity ofexternally heated tubes 2 through which the coal passes in parallel flowwith modied combustion gases; a coal charging spout 3; a hot gaslconnection 4 entering the coal feed compartment 5; a source of l40 hotgas supply 6 for the pretreater, and a waste gas outlet rl to the stack8. The pretreater heats the coal to any desired temperature such asabout 250 C. to 350 C., and, in the case of young bituminous orsub-bituminous coals, may drive 245 .oif some of the initial volatilesconsisting of oxides oi' carbon or, in treating badly fusing coals, anoxidizing pretreatment with stack gases may be appliedto reduce thefusing tendency.

The treated coal discharges into a heat insui lated feed hopper 9 fromwhich it passes through bin 10 and into magazine 11 from which it passesinto feed regulator 12 and into rotary reaction chamber 13, suitablevalves beingprovided for controlling the process, as shown. One or theother of the valves above and below bin 10 must be closed at all timesto maintain the desired pressure in the system; the top valve is openedmomentarily only while iilling bin 10 and is otherwise closed, the lowervalve being opened always excepting while bin 10 is being filled. Thevalve below magazine 11 is only for emergency in case the valve at thetop of the magazine fails to seal perfectly. The feed regulator 12 isprovidedwith a variable worm drive and gas tight stuiiing box, as shown.The pipe enclosing the worm feed passes through a revolving gas tightgland into the end of retort chamber 13. The worm feed has a hollowshaft 14 through which the escaping volatiles pass out of chamber 12 andto the fractionating condensers 15, 16, 17.

The condensers 15 are of the refiuxing insu-v lated type regulated bytemperature control, similar to petroleum practice, to condense out andreturn that portion of the tar oil vapors which has not receivedsufcient thermal decomposition in the retort. Condensed heavyhigh-boiling oils are returned continuously to the chamber 13 throughthe feed regulator 12 with the advancing supply of fresh c'oal.Condenser 16 will be regulated to condense any fractions such as acidoils containing phenols or cresols desired for special purposes whilecondenser 17 is of the parailel iiow type and will condense out thelightest naphtha.y Separator 18 is provided for continuous separation ofthe oil and water while under pressure and simultaneous removal of theilxed gases. 'Ihe valves 34, 35 and 36 on the outlets of the separator18 are regulated to 'maintain the desired pressure in the entire system.

The rotary reaction chamber 13 rests on rollers 19 at each end, and atintermediate points, which are operated by a suitable variable speeddrive 20. Instead of using rollers at the intermediate points, it may beadvisable to support the cylinder at these points by means of endlesschains passing under the cylinder and over sheaves mounted on a driveshaft above the cylinder, openings being provided through the roof ofthe enclosure surrounding the cylinder to permit the chain to pass intoand out of the enclosure. If desired chain sheaves (not shown) may bemounted on the cylinder for use with the chains as a supporting means.These chain sheaves are preferably provided with spokes of sufficientlength to permit free movement of the heating gases between them as thegases move longitudinally along the cylinder, and the length of thespokes resulting in the chain groove of the sheave wheel running in anannular recess in the brick work of the oven enclosure therebypreventing direct contact between the chain and the hot gases. Aroundthe reactionl chamber 13 lis a long oven 21 divided into separateheating zones with individual heat sources 22 and chimneys 23. Ifdesired, a part of the rotary cylinder 13 may extend beyond thel ovensand serve as a partial cooler for the coke while giving up its heat topreheat air for use in combustion. I prefer, however, to cool the cokeafter it is deposited in the receiving bin 24 by means of coils (notshown) 'through which air is passed. It will be noted that both methodsapply indirect cooling' and thereby do not provide for removal of thecontained heat of the coke by circulation of gases through the coke asis applied in dry quenching ,in my method for the heating of the coal.

methods; the recovered` heat is, however, reused The material passinginto the bin 24 is a' dry granulated coke. described, in cylinder 13 orby external means, may be immersed in a solution of copper chloride andthen returned to the chamber 13 W.th the advancing supply of fresh coalin an amount suffcient to absorb the condensed heavy high-boiling oilsand lto. desulphurize the oil. Coke from' any 'I'his coke whenactivated, as above other source may also be treated and admitted y tothe system in this manner.-

At the outlet of destructive distillation chamber 13 is an extension 25passing into fitting 26 pro-v vided with a gas-tight stumng box. At thelower outlet of fitting 26 is the pressure bin 24 with top and bottomvalves 24a and 24h respectively, the

closed at all times While the bin is filling. After lling, the valvesare reversed momentarily while the charge of coke is dropped out. At theend of fitting 26 is a plug with openings into which connections aremade for the thermocouple installation 2'7,-a.nd for pipe 28.

-Pipe 28 is provided for introducing fluids such as steam, oil, vapors,or gases into therevolving destructive distillation chamber. The pipe isprovided with side openings 29 at intervals along its length so thatit'can be made to communicate with the chamberat any point from end toend. The volatile products may if preferred be con` ducted from thedestructive distillation chamber 13 through any of the side openings inthe ppe 28 and thence to the condensers 15 by way of a pipe 33 and valve33 instead of removing them through the feed regulator 12, as describedabove.

' Saturated steam may be released at any point intermediate the end ofthe chamber 13 t'o cool and scavenge the tar oil vapors and gases. Also,by

introducing superheated steam at these intervolatiles from thecarbonaceous materials receiving treatment it is connected to the pipe33' and valve 33 at the inlet of condensers 15. Pressure gages 30 areshown on the pipes leading into and out of the reaction chamber by whichany desired pressure is governed. A pump 31 is provided at the outletfrom'condensers 15 for forcing the condensate back into the reactionchamber via pipe' 32 and feed regulator 12.

In treating some oll yielding substances I prefer to return theunder-cracked bitumens to the reaction chamber by pipe 28 which willthen be cony nected to pump 31, and thereby the cracking of thesebitumenstakes place in contact with and catalyzed by the adsorptive cokemade in the process. l

' IvhaveV found that the process operates advantageously under pressuresabove atmospheric for the reason that, rst--it reduces the amount ofundecomposed bitumens carried out of the reaction chamber suspended inthe oil vapors and gases, by reducing the quantity of volatiles producedto a smaller volume which thereby retards 2150A top one remaining'openedand the bottom one the rate at which they flow from the pores ci thecarbonaceous substances; second, the `vapor temperature of the primarybitumens is increased so that greater dissociation takes place; third,the boiling points of the bitumens subjected to further decompositionare raised to temperatures that will accomplish the dissociation to adegree required in the desired oil product. I have found that a pressureof sixty pounds gage and a temperature of 750 F. at the cold end of thereaction chamber and 950 F. in the hot zone is suited for producing atar oil from coal with the same volatility as tops from shale oil orpetroleum and which is considerably lighter than water.- This oil frommy process carries no water in suspension and is readily separated fromwater by decantation. One oil sample from Utah coal containedapproximately 20 per cent of tar acids of thesame volatility as phenoland cresol. The acid free oil contained about 35% of distillate whichwas easily refined into a sweet, -free antiknock motor fuel of excellentcolor. The residue consisted of neutral oils similar to gas oil andlight lubricants, and sludge.

By this invention, a continuous process is provided by 'which thedesired light products are continuously produced, and the cokecontinuously discharged. The coke may be' caused by regulating thedegree of pretreating, and rate o f heating, to agglomerate and. rolltogether into large cylindrical chunks.

I do not restrict myself to the treatment of coal in the claims exceptwhere specifically stated, as n any features of this invention areapplicable to the treatment of petroleum and synthetic oils.

What I claim is: y

l. A continuous process for producing hydrocarbon oil lighter than waterfrom solid carbonizable material, which comprises passing a mixture ofsolid carbonizable material and a highly adsorbtive `material containingadsorbed copper in a path oi continuous direction at a sub--I stantiallyuniform rate while excluded from the' atmosphere and maintained under apressure im terially above atmospheric, rolling the particles of mixedmaterial continuously during its aforesaid passage, heating said mixedmaterial to progressively increasing temperatures in progressive stagesof its travel effective to produce controlled pyrolysis, withdrawing thevaporized distillation products in a direction counter to the generalmovement oi the mixed material through zones of successively decreasingtemperatures, and returning incompletely decomposed liquid distillationproducts to the heating zone with additional c'arbonizable substance toeifect their further conversion.

2. A continuous process for producing hydrocarbon oil lighter than waterfrom solid carbonizable material, which comprises passing a mixture ofsolid carbonizable material and a highly adsorptive material containingadsorbed copper through a cylindrical reaction chambery of relativelygreat length and small diameter in a path of continuous direction at asubstantiallyuniform rate while excluded from the atmosphere andmaintained under a pressure materially above atmospheric, rolling theparticles of mixed material continuously during its aforesaid passage,heating said mixed material to progressively increasing temperatures inprogressive stages of its travel effective to produce controlledpyrolysis, withdrawing the vaporized distillation products in adirection coimter to the general movement of the mixed material throughzones of successively decreasing temperatures, and returningincompletely decomposed liquid distillation products to the heatingzones with additional carbonizable substance to effect their furtherconversion.

3. A process as deiined in claim 2 which further returns theincompletely decomposed liquid distillation products into the chargingend of said cylindrical reaction chamber for further treatment, and forcontinuously discharging the solid residue from said chamber withoutvarying the pressure therein.

4. A continuous process for producing hydrocarbon oils lightervr thanwater from solid carbonizable material, which comprises preheating thecarbonizable material at atmospheric pressure to reduce the fusingproperties of the material, continuously delivering the preheatedcarbonizable material to a retort while constantly eecting a sealbetween the preheated zone and the retort zone, said delivery of thepreheated material into the retort zone being forcibly effected and thetreatment in the retort zone being 'm successive stages of differenttemperatures,

continuously withdrawing vaporized distillation products from the retortzone, separating the fractions of the vapors withdrawn from the retortzone, continuously returning a heavy high-boiling oil to the retort zonefor further treatment, and' continuously removing the solid residualcoke from the retort zone while effecting a sealing of the dischargetherefrom during the removal of the solid residue.

5. A. system for producing oil lighter than water from a ,solidcarbonizable material comprising a preheating chamber, a retort,communieating means therebetween, said preheating chamber being adaptedto effect an initial pyrolysis of the carbonizable material atatmospheric pressure to reduce the fusing properties of the material,means for eecting a continuous delivery of the preheatedcarbonizablematerial to the charging end of the retort providing a sealbetween thepreheating chamber and the retort, means for forcibly feeding thematerial into the retort, said retort being of an elongatedcharacterfand provided with means for heating successive portionsthereof to different temperatures, means for continuously withdrawingvaporized distillation products from the retort at a point adjacent thecharging or discharging end thereof, means for separating fractions ofthe vapors withdrawn from the retort, means for continuously returningheavy high-boiling oils for release at several points within the retortfor further treatment, and means for continuously removing the solidresidue fromI the retort while eecting a sealing of the outlet end ofthe retort during the removing of the solid residue.

LEWIS C. KARRICK while .constantly

